From mboxrd@z Thu Jan  1 00:00:00 1970
From: Keir Fraser <Keir.Fraser@cl.cam.ac.uk>
Subject: Re: [PATCH 0/4] HVM Virtual S3
Date: Wed, 16 May 2007 23:33:51 +0100
Message-ID: <C271455F.7823%Keir.Fraser@cl.cam.ac.uk>
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On 16/5/07 22:59, "Keir Fraser" <Keir.Fraser@cl.cam.ac.uk> wrote:

>> The main idea is:
>> - emulate ACPI PM1A control resiger in QEMU to capture guest S3 request
>> - when QEMU capture guest S3 request, it call hypercall to trap to Xen
> 
> So why emulate this register in QEMU at all, rather than directly in Xen?
> Xen already knows the address of the pm1a block of ports because it emulates
> the pmtimer.

Oh, I see there is device state to be reset in QEMU. Emulating the port
access in QEMU makes sense then, but I wonder if rather than adding an extra
hypercall command we could emulate it in both Xen and QEMU: Xen emulates the
instruction, resets state and triggers domain shutdown, then passes the port
access up to QEMU so it does its thing also. We do this emulate-in-both for
other things already (e.g., the CMOS index register I believe).

 -- Keir